Technical Field
The present disclosure relates to a communication system and a channel estimating method thereof. More particularly, the present disclosure relates to a communication system, which can estimate transmission channel based on channel quality information, and a channel estimating method thereof.
Description of Related Art
Recently, multi-input multi-output (MIMO) transmission techniques are widely used in communication systems. In many MIMO transmission systems, a receiver is configured to feedback some information to the transmitter, where the feedback information may include rank indicator (RI), precoding matrix indicator (PMI) and channel quality indicator (CQI). The transmitter can set up a precoding matrix according to the above feedback information. It is noted that the term “indicator” referred to above, which has been abbreviated as “I” in the shorthands “RI,” “PMI,” and “CQI,” is sometimes termed “indication” or “index” with the same abbreviation “I.”
However, utilizing the information directly from the receivers to set up precoding matrices without further calculation can often lead to bad transmission performance because the feedback information itself frequently does not give an accurate characterization of the channel response directly. In order to achieve high transmission efficiency in a communication system, it is very important in this area to estimate the transmission channel well.